| 1. | (initial capital letter ) Mr.; Sir: a Spanish title prefixed to a man's given name. |
| 2. | (in Spanish-speaking countries) a lord or gentleman. |
| 3. | (initial capital letter ) an Italian title of address, esp. for a priest. |
| 4. | a person of great importance. |
| 5. | (in the English universities) a head, fellow, or tutor of a college. |
| 6. | (in the Mafia) a head of a family or syndicate. |

| 1. | a river flowing generally S from Tula in the Russian Federation in Europe, to the Sea of Azov. ab. 1200 mi. (1930 km) long. |
| 2. | a river in NE Scotland, flowing E from Aberdeen county to the North Sea. 62 mi. (100 km) long. |
| 3. | a river in central England, flowing NE from S Yorkshire to the Humber estuary. 60 mi. (97 km) long. |
| 4. | a male given name, form of Donald. |
| DON dissolved organic nitrogen |